Method and apparatus for determining weight and biomass composition of a trickling filter

ABSTRACT

In one embodiment, a filter media tower assembly is provided comprising a first portion and a second portion, wherein the first portion is suspended within the second portion. The first portion is a removable media tower or cage for holding filter media, whereas the second portion is a media tower guide support structure that is mounted to a surface of a tank. In a second embodiment, a load cell or a weighing assembly is disposed above the removable media tower. The deployment of this weighing mechanism above the removable media tower provides constant monitoring of biomass build-up on the filter media.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of and claims priority to and thebenefit of U.S. application Ser. No. 10/358,834, filed Feb. 5, 2003, for“Method and Apparatus for Determining Weight and Biomass Composition ofa Trickling Filter,” by Michael J. Ruppel, which is incorporated hereinby reference in its entirety.

FIELD OF THE INVENTION

The invention generally relates to the biological treatment of waterand, more particularly, relates to the operation of trickling filtersused in wastewater treatment. The invention also generally relates tocooling tower systems, air treatment systems, retention and storagebasin filtration systems, fish farms and hatcheries water filtrationsystems, or any other cooling or filtration system that utilizesstructured or random dump filtration media.

More specifically, various embodiments of the present invention relateto a method and apparatus for real-time monitoring of biomassaccumulation within stone, wood, synthetic or plastic random dump media,structured synthetic or plastic modular media, or other biomedia orbiological filter media. Random plastic or synthetic dump media andplastic or synthetic structured modular media are commonly used withintrickling wastewater filtration systems in sewerage treatmentfacilities, cooling tower systems, biological and waste water and airtreatment systems, retention and storage basin filtration systems, fishfarms and hatcheries water filtration systems, pond water filtrationsystems, and any other air or water filtration system that utilizesstructured or random media for biological growth and treatment, or anycooling tower or water cooling system that also utilizes the same orsimilar structured or random media for cooling water vapor. Unlessproperly monitored, biomass may accumulate within such media to a levelor amount under which the structured media can no longer support theincreased weight of the biomass. Under such circumstances, the media maycollapse, thereby triggering catastrophic consequences. Specificembodiments of the present invention provide a real-time means andapparatus for monitoring biomass accumulation on plastic or syntheticstructured modular or random dump media so as to avoid suchcatastrophes. Specific embodiments of the present invention also providea simple means for determining the nature and extent of the compositionand type of biomass accumulating in media under any of the above uses.

For example, one preferred embodiment of the present invention consistsof a media tower unit containing cross flow, structured modular mediawhich functions to maximize surface area to allow for microorganisms(biomass) to both grow and flourish. The individual media tower unitfits within a media tower support guide structure and is designed to beutilized in conjunction with the surrounding filtration system with easeof insertion and removal so as to not interfere with or alter theperformance of the surrounding filtration system. As wastewater isflushed through the trickling filter system and accompanying media, theindependent media tower unit assists in the monitoring of a number ofcritical variables to achieve optimum performance of the tricklingfiltration process and may be simply removed from the media towersupport guide structure for visual inspection as to the nature andextent of the composition and type of biomass accumulation. Moreover,the media tower may be suspended within the media tower supportstructure from a load cell that provides real time monitoring as to theweight and/or accumulation of biomass within the media within the mediatower.

BACKGROUND OF THE INVENTION General Background as to the BiologicalFiltration Process

The biological treatment of wastewater for the removal ofoxygen-demanding carbon and nitrogen compounds has been practiced in theUnited States for several decades. Although there are several types oftreatment systems available, the trickling filter is among the devicesmost commonly used to reduce levels of biochemical oxygen demand (BOD)and total suspended solids (TSS) in wastewater. In addition, tricklingsystems are commonly used in the oxidation of ammonia to nitrates.Examples of such filters may be found in U.S. Pat. No. 2,642,394 (issuedJun. 16, 1953 to Paulette et al.); U.S. Pat. No. 3,275,147 (issued Sep.27, 1966 to Gilde); U.S. Pat. No. 3,596,767 (issued Aug. 3, 1971 toAntonie); and U.S. Pat. No. 4,486,310 (issued Dec. 4, 1984 to Thornton).

The conventional trickling filter utilizes a film of biomass fixed on afilter media to remove and aerobically convert organic matter to carbondioxide, water and additional biomass and to oxidize ammonia tonitrates. The filter media typically comprises rock, wood, or corrugatedplastic that maximizes the surface area of biomass for wastewatertreatment. New construction of trickling filters uses predominantlyplastic modules at depths of at least five feet to higher than fortyfeet.

Trickling filters attempt to duplicate the natural purification processthat occurs when polluted wastewater enters a receiving stream andtrickles over a rock bed or rocky river bottom. In the naturalpurification process, bacteria in the rock bed remove the solubleorganic pollutants and purify the water stream. For more than 100 years(since the late 1880s), trickling filters have been considered aprincipal method of wastewater purification for pollutant removal. Theprinciple of using a rock bed for purification was applied in filterdesign with the use of rock beds generally ranging from 3 to 8 ft indepth. After declining use in the late 1960s and early 1970s, tricklingfilters regained popularity in the late 1970s and early 1980s primarilybecause of new media types. The new high-rate media were generallypreferred over rock media because the former offers increased surfacearea for biological growth and improved treatment efficiency. The adventof high-rate media minimized many of the past problems with rock media,such as plugging, uncontrolled sloughing (natural shedding or discardingof excess biomass accumulation), odors, and filter flies. Consequently,almost all trickling filters constructed in the late 1980s have been ofthe high-rate media type.

While there is a long history relative to the use of trickling filters,there are a number of modernizations that have taken place in theindustry. They include, new types of filter media, new methods regardingthe trickling filter process and its incorporation into wastewaterfacilities and the fact that many rock filters are being refurbished forcontinued use.

The purpose of the biological processes described is to remove dissolvedorganics and finely divided organic solids from wastewater. Removaloccurs primarily by conversion of soluble and colloidal material into abiological film that develops on the filter media.

In principle, the trickling filter process has the biomass attached to afixed medium. Recycling of the settled biomass is not required. Theprocess depends on the biochemical oxidation of a portion of the organicmatter in the wastewater to carbon dioxide and water with the remainingorganic matter being incorporated into the biomass itself with theenergy produced being released into the medium as heat.

The trickling filter serves as a secondary filtration method in whichpre-treated wastewater is applied to the filter medium through which theflow percolates. As the pre-treated wastewater passes through the filtermedium, the surface of the media quickly becomes coated with viscous,jelly-like, slimy substance containing bacteria and other biota. Thebiota removes organics by absorption and assimilation of soluble andsuspended constituents. After an initial start up period, the microbialbuild up may create an anaerobic interface with some of the filtermedia. This furthers the growth of facultative and possibly anaerobicorganisms.

The quality and quantity of the biomass produced is controlled by amountand nature of the available food. The amount of biomass on the mediasurface increases as the organic load and strength increase until amaximum effective thickness is reached. The maximum thickness iscontrolled by physical factors, including hydraulic dosage rate, type ofmedia, type of organic matter, amount of essential nutrients present,temperature, and the nature of the biological growth. It is important tonote, that during the filter operation, a portion of the biologicalslime sloughs off, either periodically or continuously. An accumulationof excess biomass that cannot retain aerobic condition, impairsperformance. Continuous and uniform sloughing, as measured by tricklingfilter effluent, provides an indication of a properly operatingtrickling filter.

The recirculation of trickling filter effluent has been shown to be aneffective method of improving filter efficiency by allowing for anincreased hydraulic flow rate. This in and of itself, provides improveddistribution and reduces the likelihood of dry or partially wettedsurface areas within the filter. It also allows for the sufficient shearforce to slough off excess growth reducing clogging problems associatedwith solids accumulation. There is also the possibility that the organicmatter may have missed exposure to the biomass the first time throughand may be treated a second time around. Recirculation can serve severalpurposes including, reducing the strength of wastewater being applied tothe filter; increasing the hydraulic load to reduce fly, snail, or othernuisances; maintaining movement of the distributor during low flow;producing hydraulic shear to encourage soughing of solids and preventionof ponding; diluting toxic wastes, if present; reseeding the filter withmicrobial population; providing uniform distribution of flow; andprevent filters from drying out.

The removal of soluble organic material is a relatively rapid process.Good removal of soluble organics can generally be achieved at low tomoderate loading of the fixed-film reactors. However, the stabilizationor breakdown of biological solids generated in removing the solubleorganics is a longer process. The time required for completion of thisprocess will vary depending on the type of filter media being used, rateof organic loading to the fixed-film reactor, hydraulic shear,temperature, and other factors.

Microorganisms and other forms of biological life are the active agentsfor converting the organic carbon and nitrogen into environmentallyacceptable products. As a result, a number of operating parametersaffect the efficient operation of trickling filters, includingtemperature, organic loading, filter depth, and biomass thickness.Specifically, an increase in biomass thickness creates severalchallenging criticalities.

First, existing trickling filter systems suffer from an inability toaccess biomass growth on filter media for samples and testing. Becausethese systems are relatively fixed in place once constructed and do notcontain selectively removable media, the precise organic composition ofthe biomass is extremely difficult to determine. Furthermore, becausesome specific types of organisms are desirable in biomass growth andsome are not, the ability to determine which types of organisms arepresent, and in what quantities, would be a significant aid instructuring the maintenance operations of the filtration system andcontrolling the quality of the effluent.

Second, excessive biomass accumulation can lead to the collapse offilter media and consequently the failure of the system, creating anenvironmental hazard. This, in turn, can result in governmental finesand penalties to the system operator(s) and require significantexpenditure for clean up and repair. Specifically, biomass accumulateson filter media as wastewater is passed through the filter and organicmaterial is removed. Periodically, the weight of accumulated biomassbecomes so great that a portion of the biomass sloughs off the filtermedia and accumulates downstream (i.e., beyond the filter media); thatis, the biomass thickness is effectively self-regulating. However,sloughing does not occur until a substantially large amount ofadditional biomass has already accumulated. It would be desirable to beable to accurately monitor biomass weight so that it may be regulatedand controlled from the outside, allowing the biomass to be reducedbefore it reaches a critical accumulation that may threaten stability ofthe system.

Third, excess biomass accumulation may also threaten the efficiency ofthe trickling filter system. As the thickness of accumulated biomass ona filter media increases, it reduces the effective aerobic surface areaof the filter media; as much as ninety to ninety-five percent of thetotal biomass surface may serve no useful purpose in the organic removalprocess. In addition to compromising the efficient functioning of thefilter, the accumulated excess biomass may also produce unpleasantodors, attract flies, snails, and other unwanted organisms, and discolorfilter effluent. As previously stated, the weight of accumulated biomassoccasionally becomes so great that a portion of the biomass sloughs offthe filter media and accumulates downstream. However, as also stated,sloughing does not occur until a substantially large amount of inactivebiomass has already accumulated. Therefore, to maintain optimumefficiency, it is desirable to continually control the biomass thicknessto minimum levels, eliminating as much of the anaerobic biomass as ispossible.

Finally, the maintenance of trickling filter systems is extremelyimportant, but also very expensive and time-consuming in existingsystems. This is due in large part to the great amount of uncertaintyassociated with the state of the filter media. Because it is verydifficult to access the filter media once the filter tank is constructedand in operation, it is very difficult to ascertain when maintenance isnecessary, as well as what type of maintenance and how much time isrequired to restore the system to optimal efficiency. In the past,systems have tried to control biomass growth and to maintain efficiencythrough inconsistent and intermittent dosing or flushing of the filtermedia, with mixed results. Thus, the ability to access the filter mediafor maintenance purposes would allow maintenance operations to be moreexactly tailored to address specific issues, achieving more efficientoperation of the system.

It should be noted that while a primary embodiment of the presentinvention is disclosed as used in a trickling filter of a wastewatertreatment system, other embodiments of the invention show that there isalso a need for the invention for use with cooling tower systems,biological and wastewater and air treatment systems, retention andstorage basin filtration systems, fish farms and hatcheries waterfiltration systems, pond water filtration systems, or any other air orwater filtration system that utilizes structured or random media forbiological growth and treatment, or any cooling tower or water coolingsystem that also utilizes the same or similar media for cooling watervapor where unwanted biological growth may occur within the media. Assuch, the present invention is meant to be incorporated into theseadditional filtration and cooling systems.

Description of the Filtration System

The structure, distribution, and support system used with the filtermedia are collectively named either a trickling filter or biotower. Theterm trickling filter generally applies to filters that are relativelyshallow (4 to 10 ft deep ); filters with depths greater than 10 ft areusually referred to as a biological tower or biotower. A similar term,biofilter, sometimes refers to filter towers where biological solidsfrom an activated sludge system are recycled over the filter media.

Six basic components common to all trickling filter and biotower systemsare the distribution system, filter media, under drain system,containment structure, filter pump station, and secondary clarifiers. Amore detailed description of the individual basic components associatedwith all trickling filter systems follows.

A. Distribution Systems

The two basic types of distribution systems are fixed nozzle and rotarydistributor. Fixed nozzle distributors were frequently used during theearly to mid-1900s. Presently, their use is limited to small facilitiesor package plants.

Fixed nozzle distributors consist of a piping system, often supportedslightly above the top of the trickling filter media, that feedswastewater and recycle from a pumping station through spray nozzles. Anumber of advancements in fixed nozzle design include springs, balls, orother mechanisms to evenly distribute wastewater at various flows. Evenwith these improvements, obtaining even distribution with a fixed nozzledistribution system is more difficult than with rotary distributionsystems. Fixed distributor systems have also declined in use because ofdifficult access to the nozzles for cleaning. Also, larger flow volumesmust be maintained with a fixed system to ensure good distribution.

Rotary distributors consist of a center well (usually of metal) mountedon a distributor base or pier. The distributor generally has two or morearms that carry the pumped wastewater to varying sized orifices fordistribution over the media surface. The thrust of the water spraydrives the filter arms forward. Speed-retardant back-spray orifices areoften used to adjust the rotational speed of the distributor whilemaintaining the desired pumping rate to the filter. The distributorsupport bearings are located at either the top of the mast of at thebottom of the turntable. Both types of bearings are widely used.

Typical distributor operation in the U.S. over the past 30 to 40 yearsused a rotational speed of 0.5 to 2 min/rev. With two or four arms, thefilter is dosed every 10 to 60 seconds. Recent evidence indicates thatdecreased dosing frequency from reduced rotational speeds can beadvantageous in many situations. In fact research has indicated thatslowing the distributor reduces excess biofilm storage, reduces odors,and likely improves the operation of the plastic media filters. Theoptimum flush rate is still to be defined and, to a degree, may be siteand application specific.

B. Filter Media

The introduction of synthetic or plastic media for trickling filters hasextended the ranges of hydraulic and organic loadings well beyond thoseof stone media. Two media properties of interest are specific surfacearea (surface area/unit volume) and percent void space. A greaterspecific surface area permits a larger mass of biological slime per unitvolume. Increased void space allows higher hydraulic loadings andenhanced oxygen transfer. The ability of synthetic media to handlehigher hydraulic and organic loadings is directly attributable to thehigher specific surface area and void space of these media.

Unlike rocks or wood media, the increase in slime thickness on plasticmedia reduces the aerobic biological surface area. Thus, as the specific(clean or unused) surface area increases, the area used for aerobicgrowth begins to decrease.

The media itself can be designated as rock, horizontal wood slats,random plastic modules (often referred to as “random dump media”), orstructured plastic modules such as vertical fully corrugated bundles orcross-flow media modules. In addition, vertical semicorrugated mediawith alternate flat sheets in the bundle have been widely used. Verticalfully corrugated and vertical semicorrugated media were the primarysynthetic media from the late 1950s to the early 1980s. Since then,cross-flow media has become the most popular type. Vertical fullycorrugated media is used for stronger wastes and more highly loadedfilters.

C. Underdrain System

The underdrain system supporting rock media usually consists of precastblocks laid over the entire sloping bottom of the filter floor.Underdrain and support systems for high-rate media generally consist ofa network of concrete piers and support stringers placed with theircenters 1 to 2 ft apart. Redwood or pressure-treated wood materials arealso used as underdrain material.

Underdrains for plastic or high-rate filter media are generally 1 to 2ft in depth to allow air movement to the interior of the filter. Floorsgenerally slope downward to a collection trough that carries wastewaterto an outlet structure. The collection trough also serves as an airconduit to the interior of the trickling filter. Access to the filterunderdrain system should be available at the outlet box to allowperiodic inspection.

D. Containment Structure

The housing for rock media usually consists of poured-in-place concrete.Filter towers are lightweight containment structures consisting ofprecast concrete, fiberglass panels, or other materials. Thesestructures are used with high-rate media that are self-supporting (exertno wall pressure).

The wall of the containment structure often extends 4 to 5 ft above thetop of the filter media. This prevents spray from staining the sides ofthe filter tower and reduces wind effects when cooling reduceswastewater temperatures.

In the U.S., rock filters are typically 3 to 6 ft deep and occasionally8 ft deep. This depth limitation is associated with lack of adequateventilation produced by natural draft as well as an increased tendencyto pond. In Europe, rock filters are commonly used.

Plastic media trickling filters are most commonly constructed between 16to 26 ft deep, although units up to 42 ft deep exist. The limiting depthis associated more with the tower height aesthetics, serviceability,pumping requirements, and structural design of the media than withbiological treatment efficiency. Increasing the depth of the filter isgenerally worthwhile to reduce the minimum flow required for wettingand, thus, reduce recirculation. In taller filters that have highloadings, oxygen deficiency may occur in the uppermost layers. However,adequate ventilation and hydraulic flushing prevent odor problems fromdeveloping.

The effect of media depth on filter performance is a controversialtopic. Deeper filters tend to have higher average hydraulic rates and islikely the primary reason for their better volumetric performance.

E. Filter Pump Station

As an integral part of the trickling filter or biotower system, thepumping station usually lifts the primary effluent and the recirculatedfilter effluent, if any, to the top of the media. Much less frequently,dosing tanks or gravity feed are used for that purpose. The filter pumpsmost commonly used are vertical-turbine units mounted above a wet well.Submersible pumps and dry-pit centrifugal pumps may also be used in thefilter pump station.

The trickling filter is generally elevated so that the hydraulic gradeline allows gravity flow to the secondary clarifier or other downstreamtreatment units. If recirculation is used, the downstream treatment unitor clarifier generally controls the water level in the pump station wetwell so that a control valve is not necessary to modulate the amount ofunderflow returning to the filter pumps.

As an often important element in trickling filter design, a portion ofthe trickling filter effluent is recycled through the filter. As notedearlier, this practice is known as recirculation and the ratio ofreturned flow to incoming flow is called the recirculation ratio.Recirculation is an important element in stone filter design because ofapparent increases in the BOD removal efficiency and is important insynthetic media filter design because it can ensure that the filter isadequately wetted. Many types of recirculation arrangements have beenand are used in trickling filter designs.

Recirculation in stone media trickling filters increases BOD removalefficiency for a variety of reasons. Organic matter in recycled filtereffluent contacts the active biological material on the filter more thanonce. This increases contact efficiency and seeds the filter throughoutits depth with a large variety of organisms. If the recirculated flowpasses through a settling tank, it dampens variations in loadingsapplied to a filter over a 24-hour period. Because the strength of therecirculated flow lags behind that of the wastewater, recirculationdilutes strong wastewater and supplements weak wastewater. This helps tomaintain the filter in good condition during periods of fluctuation inloading. Recirculation through primary tanks tends to freshen stalewastewater and reduce scum formation. Also, continuous recirculation tothe primary tank from the sludge hopper of the secondary settling tankremoves sludge and reduces oxygen depletion in plant effluent.Recirculation improves distribution over the surface of filters, reducesclogging tendency, and, if sufficiently high, aids in the control offilter flies. Therefore, providing recirculation where none existsfrequently results in the securing the desired degree of treatment withonly a slightly higher operating cost. Finally, and perhaps mostimportantly, the increase in applied total flow increases the wettingefficiency.

F. Secondary Clarifer

Performance of the trickling filter generally depends not on soluble BODremoval, but on the ability of the secondary clarifier to separate thesuspended solids from the treated wastewater. This is especially truefor low intermediate-, and even those high-rate filters that remove mostof the soluble BOD. Effluent quality therefore depends largely on theparticulate BOD associated with solids remaining in the clarifiereffluent.

With the trickling filter process, past practices have resulted insecondary clarifiers with high hydraulic overflow rates and shallowsidewater depths 8 to 10 ft. Corresponding suspended growth systems wereoften designed with clarifiers having much lower hydraulic overflowrates and sidewater depths of 10 to 12 ft. As trickling filter plantsare now required to achieve secondary or even higher treatment levels, atrend to deepen the clarifier sidewater depth is necessary and willlikely occur to provide a greater separation zone for solids removal.Likewise, reduced overflow rates may be needed to achieve the requiredeffluent quality.

NEED FOR THE PRESENT INVENTION

Even though the trickling filter process is considered to be one of themost trouble free means of secondary treatment, the potential foroperating problems exists. The source of mechanical problems is oftenobvious. However, less obvious causes of problems may stem fromoperations, design overload, influent characteristics, and othernon-equipment related items.

An unprecedented number of trickling filter collapses have occurred inthe past decade. The most common cause of the failure as noted by DennyS. Parker in the abstract “Trickling Filter Mythology” as found in theJuly 1999 Journal of Environmental Engineering, was actually weak media.Of the 12 “catastrophic” collapses studied, seven involved poor qualitycontrol relating to the supplier of the particular media involved. Threeof the seven instances involved vertical flow media and four had crossflow media.

A method to evaluate sloughing and low rate trickling filterapplications with corrugated plastic sheet media is needed todemonstrate the benefits, if any, of daily flushing cycles withmotorized distributors. In addition to the typical performance (odors,process efficiency), the amount of biomass accumulation should bemeasured directly rather than by inference. With the present invention,this is accomplished by equipping full-scale trickling filters with loadcells containing the various media types. The load cells allow fordirect determination of biomass accumulation as a function of processparameters. The influence of slowed distributor speed and a number ofother factors as previously highlighted, could be accessed so as todetermine trickling filter optimization for a particular seweragetreatment facility.

Good records and data associated with the trickling filter are essentialin locating, identifying, and applying the proper corrective measure tosolve problems. Tracking soluble BOD, TSS, pH, temperature, and otherparameters may be necessary to recognize trends that result in adverseeffects on the trickling filter. Other common operating problems mayresult from increased growth, changes in wastewater characteristics,improper design, or equipment failures.

The present invention will enable a plant operator to address these andother issues through a real time measurement system. These issuesinclude, but are not limited to, methods to assess biomass development,determine the optimum flushing rates and distributor speed optionsfriendly to the biomass itself and to promote optimal sloughing andaddress concerns regarding media performance.

The within invention would not only allow for such real time monitoring,but also provides an opportunity to extract individual media towers thatcontain the media used in the system from the media tower support guidestructure for visual observation and to provide an opportunity toperform a microscopic evaluation of the biomass itself. Also, thedistribution of several individual media towers throughout differentquadrants of the filtration tank allows for the collection of additionaldata and more accurate measurements as to biomass growth, in terms ofweight, type and composition.

The present invention further allows for the monitoring of the biomassat multiple depths within the filtration system and at various intervalsalong the radius of the trickling filter tank, thereby allowing forevaluation of different types of media under the same applications atvarious depths within the tank, within different types of media, atvarious quadrants with the tank, and at various locations along theradius of the trickling filter tank. The data acquired would then beused to both evaluate the efficiency and life expectancy of the existingmedia. The use of multiple media modules within a media tower providesreadily available culture sampling points within the trickling filtermedia tower at various depths in the system tank and also at variouspoints along the radius of the system tank. With this, comes easy accessto conduct microscopic examinations, means to observe underdrainconditions, and a means to easily evaluate the potential for filamentousgrowth.

Recently, designs have attempted to measure the weight of filter mediaby placing weighing devices (essentially scales) beneath a stack ofmedia modules or beneath a media tower containing media modules;however, these designs result in somewhat precarious structures, andretrieval of the weighing devices for maintenance or repair is difficultand time consuming due to the position of such devices. A furtherproblem is retrieval of the filter media itself for maintenance andmonitoring—such attempts at weighing the structures still do notadequately address this problem, nor have any other suitable solutionsbeen offered. Moreover, such attempts to measure biomass accumulationwithin a media segment or stack have proven unsuccessful.

Thus, there is a need in the art for a means that can accurately andefficiently measure the nature and extent of biomass weight, type andcomposition on trickle filter media, so that operation of the tricklingfilter system may be optimized. Furthermore, it would be useful todevise such a system in which maintenance is relatively easy and doesnot significantly interrupt the treatment process. The present inventionfulfills this need.

It should be noted that while a primary embodiment of the presentinvention is disclosed as used in a trickling filter of a wastewatertreatment system, other embodiments of the invention show that there isalso a need for the invention for use with cooling tower systems,biological and wastewater and air treatment systems, retention andstorage basin filtration systems, fish farms and hatcheries waterfiltration systems, pond water filtration systems, or any other air orwater filtration system that utilizes structured or random media forbiological growth and treatment, or any cooling tower or water coolingsystem that also utilizes the same or similar media for cooling watervapor where unwanted biological growth may occur within the media. Assuch, the present invention is meant to be incorporated into theseaddition filtration and cooling systems.

DISCUSSION OF THE PRIOR ART

It should be highlighted that while there are a number of prior artreferences which relate to treatment of secondary waste water, none ofthe noted references relate in any way to a method and apparatus forreal time monitoring of biomass weight, composition and type within themedia of a trickling filter. In particular, none of the prior artreferences relate to a method and apparatus for real time monitoring ofbiomass accumulation within any form of media used in secondarytrickling wastewater filtration systems in sewerage treatmentfacilities, cooling tower systems, biological and wastewater and airtreatment systems, retention and storage basin filtration systems, fishfarms and hatcheries water filtration systems, and any other filtrationthat utilizes structured or random media for biological growth andtreatment, or any cooling tower or cooling system that also utilizes thesame or similar structured or random media for cooling water vapor whereunwanted biological growth may occur within and upon the media. Thepresent invention provides that utility.

U.S. Pat. No. 5,096,588 (issued Mar. 17, 1992 to Albertson) relatesgenerally to the biological treatment of wastewater and particularly toa method and system for optimizing the operation of a trickling filter.The object of the invention is to provide optimal flushing intensity forwastewater treatment and the flushing of biomass without having tocontinually monitor and control a multitude of operating variables. TheAlbertson invention utilizes various timers and controllers, noted to bereadily available on the market, which would in essence monitor thewastewater system once the optimal SK value has been determined.

U.S. Pat. No. 5,232,585 (issued Aug. 3, 1993 to Kanow) references adenitrification system and utilizes multi-stage systems and methods forthe treatment of water for biological denitrification and suspendedsolids removal. This process is accomplished through the use of abiological reactor with multiple chambers, which would then fit into awastewater treatment plant to obtain the desired results.

U.S. Pat. No. 5,057,221 (issued Oct. 15, 1991 to Bryant) references anaerobic biological dehalogenation reactor in which an aqueous mixture ispassed through the bioreactor containing a mixed microbial populationsupported on a substrate bed. Organic compounds, which are present inthe aqueous mixture and passing through the reactor, would then bebroken down.

U.S. Pat. No. 5,282,381 (issued Feb. 1, 1994 to Krone-Schmidt)references a supercritical fluid contamination monitor. As noted by itstitle, the claimed invention provides a system and method for thedetection of contaminants in a supercritical fluid. The fluid itself ispassed through an absorbent module that would absorb the contaminants tothe extent that there are any. By measuring the electrical properties ofthe absorbent material, the contaminant levels could be measured andmonitored. The electrical properties of the absorbent would vary basedupon the level of contaminants absorbed by the module itself. While theKrone-Schmidt Patent does encompass a method of detection and monitoringwith respect to contaminants, this prior art does not reference any formof real time monitoring and/or determination of biomass weight, type andcomposition.

U.S. Pat. No. 5,395,527 (issued Mar. 7, 1995 to Desjardins) references aprocess and apparatus for treating wastewater in a dynamic, biosequenced manner. The Desjarins invention involves a multiple stepsystem including; (1) a filling step; (2) reaction step; (3) settlingstep; and (4) a decantation step. More specifically, wastewater is firstintroduced into a reactor, which leads to the reaction step wherein thebiomass has an opportunity to absorb any organic materials that might bepresent. The third step is to allow the activated solids to settle sothat the treated water may be removed from the top of the reactor, perstep four.

U.S. Pat. No. 5,885,460 (issued Mar. 23, 1999 to Dague) refers to anaerobic migrating blanket reactor. The invention encompasses acontinuously fed compartmentalized reactor that reverses its flow in ahorizontal fashion and allows for the anaerobic treatment of wastes.

Finally, U.S. Pat. No. 6,146,531 (issued Nov. 14, 2000 to Matheson)references a process and apparatus for biologically treating water. Thismultiple step process comprises the introduction of a sulfur containingoxygen scavenger to water, removing the substance from the water by theintroduction of microorganisms, and the feeding of a biostimulant to themicroorganisms to increase the rate of reaction. The apparatus claimedcomprises the system by which the scavenger and the microorganisms areintroduced. Like the other noted patents, there is no reference to anyform of real time biomass monitoring and/or weight determination.

Based upon the aforementioned, there remains a need for a monitoringsystem for the treatment of water which would not only measure the realtime weight, type and composition of biomass, but also monitor aparticular system for optimal flow capabilities.

SUMMARY OF THE INVENTION

In one embodiment, the invention provides a filter media tower assemblycomprising a first portion and a second portion, wherein the firstportion is suspended within the second portion. The first portion is aremovable media tower or cage for holding filter media, whereas thesecond portion is a media tower guide support structure that is mountedto a surface of a tank, usually the bottom of the filtration tank. Themedia used may be corrugated structural plastic media, random dumpmedia, stone, or any media commonly used in the art of trickling filtersor water cooling systems.

In a second embodiment, a load cell or a weighing assembly is disposedabove the removable media tower. The deployment of this weighingmechanism above the removable media tower provides constant monitoringof biomass build-up on the filter media.

In a third embodiment, the removable media tower for holding filtermedia may be removed from the second portion media tower at variousintervals for inspection of the nature and extent of weight, type andcomposition of the biomass accumulated on and in the media. Mediaintegrity may also be examined at various vertical integrals for anypotential compromises. In addition, the performance and efficacy ofvarious media types may be inspected at various depths within a singlemedia tower by visual and microscopic analysis of biomass build-up, typeand composition.

There has thus been outlined, rather broadly, the more importantfeatures of the invention in order that the detailed description thereofthat follows may be better understood, and in order that the presentcontribution to the art may be better appreciated. There are, of course,additional features of the invention that will be described hereinafterand which will form the subject matter of the claims appended hereto.

In this respect, before explaining at least one embodiment of theinvention in detail, it is to be understood that the invention is notlimited in its application to the details of construction and to thearrangements of the components set forth in the following description orillustrated in the drawings. The invention is capable of otherembodiments and of being practiced and carried out in various ways.Also, it is to be understood that the phraseology and terminologyemployed herein are for the purpose of description and should not beregarded as limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited embodiments of theinvention are attained and can be understood in detail, a moreparticular description of the invention, briefly summarized above, maybe had by reference to the embodiments thereof which are illustrated inthe appended drawings. It is to be noted, however, that the appendeddrawings illustrate only typical embodiments of this invention and aretherefore not to be considered limiting of its scope, for the inventionmay admit to other equally effective embodiments.

FIG. 1 illustrates a top view of a trickling filter tank of oneembodiment of the invention;

FIG. 2 illustrates an isometric view of a trickle filter media tower ofone embodiment of the invention;

FIG. 3 illustrates a top view of a trickle filter media tower;

FIG. 4 depicts a single sheet of a plastic trickle filter media whereinsaid sheets are “welded” or spot-glued together to form corrugatedbundles of cross-flow structured media “modules” or blocks;

FIG. 5 illustrates an exploded view of a load cell for use with oneembodiment of the invention;

FIG. 6 is a modified riser diagram of a biomass monitoring systemaccording to the present invention; and

FIG. 7 is a block diagram of a general purpose computer used inembodiments of the present invention.

FIG. 8 illustrates the media tower being extracted from the media towerguide support structure for examination.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 illustrates a top view of a trickling filter tank 100 of oneembodiment of the invention. The tank is similar in function to thatdescribed in U.S. Pat. No. 5,096,588 (“Method And System For OptimizingThe Operation Of A Trickling Filter”, issued Mar. 17, 1992 toAlbertson). In another embodiment, the tank may be a cooling towerstructure for cooling water vapor. Other specific and particularembodiments include biological and wastewater and air treatment systems,retention and storage basin filtration systems, fish farms andhatcheries water filtration systems, pond water filtration systems, andany other filtration system that utilizes structured or random media forbiological growth and treatment, or any cooling tower or water coolingsystem that also uses the same or similar structured or random media forcooling water vapor where unwanted biological growth may occur withinthe media.

The tank 100 is constructed of a water impervious material—typicallyconcrete or steel—and is generally circular in shape. The interior ofthe tank 100 is filled with a filter media (shown in more detail in FIG.2) such as loose stones, wood, or synthetic or plastic media. Theplastic media may be comprised of, but is not limited to, random plasticmodules, often referred to as random dump media, or structured plasticmodules such as vertical fully corrugated bundles, cross-flow mediamodules, or vertical semicorrugated plastic media modules with alternateflat sheets in the bundle. One or more distributor arms 102 extend fromthe center point C of the tank 100 across the radius of the tank, andrevolve 360 degrees, distributing wastewater over the top surface 104 ofthe filter media. A trickling filter tank 100 contains at least onedistributor arm 102, but more typically, a trickling filter tankcontains four distributor arms 102 for even water flow and distributionthrough the filter media in the filter tank.

FIG. 2 illustrates a filter media tower assembly 200 comprising a firstportion 208 and a second portion 210, wherein the first portion 208 issuspended within the second portion 210. The first portion 208 is aremovable media tower or cage 212 for holding filter media 204, 206,whereas the second portion 210 is a media tower guide support structurethat is mounted to a surface of the tank, usually the bottom (100 inFIG. 1). In one embodiment, the tank 100 further comprises a pluralityof trickle filter media tower assemblies 200, as shown in FIG. 2. Atleast one of these media towers assemblies 200 comprises a removablemedia tower 212 that is suspended from a load cell assembly 202(illustrated in greater detail in FIG. 5) for monitoring the weight ofthe removable media tower. Although only one (1) filter media towerassembly 200 may be used, the utilization of more than one (1) towerassembly 200 in a water filtration system or water cooling tower systemwill provide a more representative picture of biomass growth since moredata as to biomass weight, type and composition can be monitored andobtained. Distributing a plurality of media tower assemblies 200throughout different quadrants of the filtration tank 100 at variousradii from the center point C of the filtration tank 100 allows for thecollection of additional data, is more representative of, and furtherallows for more accurate measurements as to biomass growth in terms ofweight, type and composition. The tank 100 depicted in FIG. 1 featuresfour such load cells L₁, L₂, L₃ and L₄, which are dispersed at variousdistances from the center point C of the tank 100 to give representativevalues for media tower weights in various sections of the tank 100.

FIG. 2 illustrates an isometric view of a trickle filter tower assembly200 of one embodiment of the present invention. The tower assembly 200comprises a first portion media tower 208 and a second portion mediatower guide support structure 210, both of which are substantiallyhollow and rectangular in shape. However, the present invention is notso limited—the first and second portions 208, 210 may be deployed withother shapes, e.g., cylindrical. The cross sections of each portion 208,210, taken along lines A—A and B—B are square. The first portion mediatower 208 is suspended from a load cell assembly 202 and “floats” withinthe second portion media tower guide support structure 210, which servesas a guide support structure that maintains the first portion 208 inproper alignment. The load cell assembly 202, with its support bracket500, is mounted to the top portion of the media tower 208, therebyallowing the media tower 208 to freely suspend within said guide supportstructure 210, is discussed in greater detail in FIG. 5.

The first portion 208 comprises a media tower (essentially a metal cage)212, preferably manufactured from any rigid, structurally strong andnon-corrosive material such as aluminum, stainless steel, rigid andstructurally strong synthetic composite materials, and the like, thatdefines a volume 214 therein. The volume 214 contains several layers,blocks or modules of structured synthetic trickle filter media 204, 206.In the illustrated embodiment, the filter media comprises blocks formedfrom corrugated plastic sheets such as the ACCU-PAC® flow mediacommercially available from Brentwood Industries of Reading,Pennsylvania. Alternatively, the filter media may comprise loose stonesor wood—i.e., any media that maximizes the surface area for aerobicbiomass accumulation. The layers 204, 206 may be arranged so that theydrain in alternating or differing directions to maximize cross flow.Cross-bracing 216 extends across each outwardly facing surface of themedia tower 212 to reinforce the stability of the tower 212 and toretain the filter media 204, 206 within the tower 212. The nature andextent of cross bracing 216 required is dependent on the nature of themedia used. For example, stone media would require additional crossbracing 216 due to that media's weight and size and due to the fact thatsuch media is “loose,” as opposed to “structured.” However, relativelylightweight, large plastic cross-flow module media would require muchless cross bracing 216.

The first portion media tower 208 of the tower assembly 200 is suspendedfrom a load cell assembly 202. The load cell assembly 202, illustratedin greater detail in FIG. 5, measures by tension the weight of the firstportion media tower 208 of the tower assembly 200 and sends thisinformation to a central processing unit (CPU, shown in FIG. 6). In thismanner, the approximate weight of accumulated biomass on the filtermedia 204, 206 can be gauged, thereby allowing for a more accuratemonitoring of the trickling filter system. Furthermore, as opposed todesigns that weigh the tower assembly 200 from below, the load cellassembly 202 of the illustrated design may be easily retrieved orreplaced without having to suspend operation of the filter system forany substantial period of time, as is shown in FIG. 8. This design alsoavoids accounting for the weight of the support structure, or ofsuperfluous biomass that has sloughed off the filter and fallen to thebottom of the tank. Thus, “real time” biomass growth rates can beascertained and monitored.

The second portion media tower support guide structure 210 of the mediatower assembly 200 is a guide support structure or base that comprises acage 218 with cross bracing 220 on each outwardly facing surface toreinforce stability. The nature and extent of cross bracing 220 requiredis dependent on the nature of the media used. For example, stone mediawould require additional cross bracing 220 due to the media's addedweight. However, relatively lightweight plastic cross-flow module mediawould require much less cross bracing 220. The cage 218 comprises anupper segment 226 and is, in this embodiment, substantially rectangularin shape, having four corners 224 with a leg 222 at each corner 224 thatsupports the cage 218 above the tank floor (not shown). The load cellassembly 202, attached to the first portion media tower 208, contains anupper bracket 500 (discussed in greater detail with regard to FIG. 5),which contains a downward vertical element or plate 502 on each side ofthe bracket that readily slides into a receiving element 228 mounted oneach of the four (4) sides of the upper segment 226 of the support guidestructure 210. As such, by virtue of the support bracket 500 and itsside plates 502 locking into the receiving elements 228 on the uppersegment 226 of the support guide structure 210, the inner media tower208 freely hangs or is suspended within said support guide structure210. The legs 222 of the support guide structure 210 are anchored into asurface of the tank 100, e.g., the concrete slab that forms the floor ofthe tank 100, by anchors 229 (shown in phantom). The perimeter of thesecond portion 210 of the tower assembly 200 is at least slightlygreater than the perimeter of the first portion 208, so that the firstportion 208 is aligned vertically within the upper segment 226 of thesecond portion 210 and essentially is suspended and “floats” within saidsecond portion 210.

A further advantage of this media tower configuration is that it iseasily removable; as the first portion 208 containing the filter media204, 206 is suspended in place, it may be easily lifted out of thefilter tank 100 for maintenance or examination. The media tower 208comprises at least one set of holes 217 drilled at an equal distancealong the length of each vertical corner support member 212. These holes217 allow the first portion 208 of the tower 200 to be lifted out of thetank and “pinned” or held in place by the use of at least two (2), andpreferably four (4), pins 219 which are inserted through the holes 221in the upper segment 226 of the second portion 210 and then through thecorresponding holes 217 in said first portion, so that the filter media204, 206 contained within said first portion media tower may be removedand examined or tested. Biomass samples may thus be easily taken fromthe filter media 204, 206 and tested to determine their organiccomposition, where the quantity and type of organisms present in thebiomass can demonstrate whether or not the filter is workingeffectively, and can dictate the type of maintenance required if it isnot. Multiple sets of holes 217 allow for biomass evaluation at variousdepths in the tower 200. FIG. 8 depicts the media tower 208 beingphysically extracted from the media tower guide support structure 210.As is shown, the entire load cell assembly 202, with upper bracket 500attached, is securely mounted to the top of the media tower 208.

The filter media 204, 206 is shown in greater detail in FIGS. 3 and 4.FIG. 3 is a top view of a media tower 300, in which the top of a mediablock layer 304 is illustrated. Media blocks 304 comprise a plurality ofcorrugated plastic sheets 410, welded together to form “holes” or pathsfor wastewater to trickle down; an individual plastic sheet 410 isillustrated in FIG. 4.

FIG. 5 is an exploded view of the load cell assembly. The assemblycomprises a load cell 506 housed in a housing (i.e., a plastic box) 504that is held in place between a first bracket 512 and a second bracket500.

The first bracket 512 is coupled to the first portion 208 of the filtermedia tower assembly, as shown in FIG. 2. A bearing device 510, forexample, a ball joint rod end, reduces friction between the firstbracket 512 and the bottom lid 508 of the housing 504. The secondbracket 500 is disposed parallel to the first bracket 512 and may bevisible above the surface of the filter tank. The second bracket 500comprises an aluminum C-channel welded at each end to an aluminum plate502, and is of a thickness sufficient to avoid excessive bowing whensupporting the weight of the removable media tower 208. Naturally,sufficiency of thickness will also be a function of the material used toform the bracket 500. The second bracket 500 contains two side elementsor plates 502, in this case aluminum plates, which support the mediatower and load cell assembly by inserting the plates 502 into receivingelements 228 (FIG. 2) mounted on each side of the upper segment 226 ofthe media tower support guide structure 210. The thickness of thebracket 500 is crucial to the effective function of the media towerassembly because it supports a good deal of the weight of the removablemedia tower. A bracket 500 that is too thin runs the risk of bowing orsnapping, and this can lead to failure of the entire media towerassembly, as well as inaccurate measurements. The required thickness ofbracket 500 and the side elements 502 are dependent on the compositionand stress factors of the bracket (e.g., aluminum, stainless steel,other alloys), the size and weight of the media tower 208, the natureand type of the media used, and other variables which, when taken intoaccount by one skilled in the art, would lead to a proper determinationof an adequately thick and strong support bracket 500 and side plates502. So, for example, if the first portion of the media tower isapproximately 7 feet in height, an aluminum bracket with a one-half inchthick C-channel would be used. The second bracket 500 is fastened to theplastic box 504 by a screw 514 or other fastening means which, asdetailed below, would likely be of the same thread size and type as theball joint rod end 510 used to suspend the media tower 208 from the loadcell 506.

The load cell 506 is housed within the housing 504 and is securedthrough the bottom of the housing 508 and into the first bracket 512,which serves as anchoring point for the load cell. The load cell 506illustrated in FIG. 5 is a commercially available S-type load cell, suchas the STC® S-type load cell available from Celtron Technologies ofSanta Clara, Calif. The load cell 506 contains a bridge circuit thatdeforms as it is loaded by tension; it sends the information back to aCPU (shown in FIG. 6) that translates this information into weightvalues for the associated removable media tower. The load cell 506, asfeatured in the present embodiment, contains an upper and lower threadedreceptacle for receiving the screw 514 mounted through the upper supportbracket 500 and the ball joint rod end 510 used to suspend the mediatower 208 by means of attachment to the media tower support bracket 512from the load cell 506. As such, the screw 514 and the ball joint rodend 510 serve as “anchors” between the load cell 506 and the media tower208 and the media tower guide support structure 210

FIG. 6 is a modified riser diagram of biomass monitoring system 600according to the present invention. In one embodiment, the biomassmonitoring system 600 is implemented using a general purpose computer orany other hardware equivalents. The biomass monitoring system 600 iscontrolled by an electrical panel 602 and comprises one or more powersupplies 604, 606, a network device or general purpose computer 610, aplurality of load cells L₁–L₄, and an output bridge sensor S₁–S₄ coupledto each load cell L₁–L₄.

The general purpose computer 610 is powered by the uninterrupted powersupply 604 and is shown in greater detail in FIG. 7. The computer 710comprises a processor 702, a memory 704 (e.g., random access memory(RAM) and/or read only memory (ROM)), and various input/output devices708 (e.g., storage devices, a receiver, a transmitter, a speaker, adisplay, etc.). A series of output bridge sensors, represented by 706,reports data from a series of load cells to the processor 702

In operation, the power supply 606 sends 110 Volts to output bridgesensors S₁–S₄, which convert the 110 Volts into a milliamp circuit. Themilliamp circuit powers the load cells L₁–L₄, which send input in theform of tension measurements back to the output bridge sensors S₁–S₄.The output bridge sensors S₁–S₄ report the data from the load cells tothe general purpose computer 610.

Once the system 600 is implemented, the computer 610 may perform avariety of functions based on the data received from the output bridgesensors S₁–S₄. For example, once the weight of a removable media tower208 has been determined, thereby establishing the baseline tare weightof the media tower 208 with filter media 204, 206 included, the amountof accumulated biomass in that tower's section of the tank can bedetermined, and appropriate maintenance operations can be deployed. Forinstance, if the weight is calculated above an acceptable value,indicating excess biomass accumulation, the computer 610 may direct theflow rate of wastewater being distributed by the distributor arm(s) (102in FIG. 1) to be increased in order to flush out the excessaccumulation. Or, system operations may be halted and the media may beexamined by extracting the media tower 208 from the media tower supportguide structure 210. Visual and microscopic inspection may revealexcessive growth of certain biota, and thus, system parameters may bechanged to move the biomass composition back into equilibrium. Mediaintegrity may also be determined upon such visual inspection.

FIG. 8 shows the media tower 208 being extracted from the guide supportstructure 210, with only the upper segment 226 of said guide supportstructure visible, as the balance of the guide support structure isembedded within and obscured by the surrounding media of the filtrationtank. As noted, the entire load cell assembly 202 (shown in detail inFIG. 5), including the upper bracket 500 and the lower bracket 512 aresecurely attached to the upper segment of the media tower 208. The uppersegment 226 of the support guide structure contains four (4) receivingelements 228 for holding the side plates 502 of the upper bracket 500 ofthe load cell assembly 202. This allows the media tower 208 to freelyhang or suspend within the support guide structure 210, thereby allowingaccurate measurements to be obtained via the load cell assembly 202.

The media tower 208 contains several holes 217 in each of the four (4)corner elements, with corresponding holes 221 in the four (4) corners ofthe upper segment 226 of the guide support structure 210. This allowspins 219 to be inserted through the outer holes 221 of the upper segment226 of the guide support structure 210 and then through the holes 217 ofthe media tower 208, thereby allowing the media tower to be securelyheld in place at various extraction intervals for inspection andsampling.

The present invention therefore represents a significant advancement inwastewater treatment and trickling filter design. The weight ofaccumulated biomass on filter media may be more accurately and easilydetermined in real time, without substantial disruption of thefiltration process. Furthermore, the removable media towers allow forinspection of actual biomass composition, as well as easy maintenance,repair or replacement of filter media. Other structures employingsimilar types of filter media, such as cooling tower systems, biologicaland wastewater and air treatment systems, retention and storage basinfiltration systems, fish farms and hatcheries water filtration systems,pond water filtration systems, or any other air or water filtrationsystem that utilizes structured or random media for biological growthand treatment, or any water cooling tower or water cooling system thatalso utilizes the same or similar media for cooling water vapor whereunwanted biological growth may occur, may likewise benefit by employingthe design disclosed herein.

While the foregoing is directed to various embodiments of the invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

As such, those skilled in the art will appreciate that the conception,upon which this disclosure is based, may readily be utilized as a basisfor the designing of other structures, methods and systems for carryingout the several purposes of the present invention. It is important,therefore, that the claims be regarded as including such equivalentconstruction insofar as they do not depart from the spirit and scope ofthe present invention.

Further, the purpose of the foregoing description and abstract is toenable the U.S. Patent and Trademark Office and the public generally,and especially the scientists, engineers and practitioners in the artwho are not familiar with patent or legal terms or phraseology, todetermine quickly from a cursory inspection the nature and essence ofthe technical disclosure of the application. The abstract is neitherintended to define the invention of the application, which is measuredby the claims, nor is it intended to be limiting as to the scope of theinvention in any way.

As to the manner of usage and operation of the present invention, thesame should be apparent from the above description. Accordingly, nofurther discussion relating to the manner of usage and operation will beprovided.

With respect to the above description then, it is to be realized thatthe optimum dimensional relationships for the parts of the invention, toinclude variations in size, materials, shape, form, function and mannerof operation, assembly and use, are deemed readily apparent and obviousto one skilled in the art, and all equivalent relationships to thoseillustrated in the drawings and described in the specification areintended to be encompassed by the present invention.

Therefore, the foregoing is considered as illustrative only of theprinciples of the invention. Further, since numerous modifications andchanges will readily occur to those skilled in the art, it is notdesired to limit the invention to the exact construction and operationshown and described, and accordingly, all suitable modifications andequivalents may be resorted to, falling within the scope of theinvention.

1. Method for monitoring the weight of a trickle filter medium, saidmethod comprising the steps of: a) suspending a first portion housingsaid trickle filter medium from a load cell assembly; and b) measuringthe tension on the load cell assembly.
 2. The method of claim 1, furthercomprising the step of converting the tension measurement to a weightvalue of said trickle filter medium.
 3. Method for monitoring the weightof a trickle filter medium, said method comprising the steps of: a)suspending a first portion housing said trickle filter medium from aload cell assembly, said load cell assembly operably connected to a topside of said first portion and to a second portion, said second portionconfigured as a guide support structure for receiving said first portionwithin a volume defined by said second portion, wherein the firstportion is suspended within the second portion; and b) measuring thetension on the load cell assembly.
 4. The method of claim 3, furthercomprising the step of converting the tension measurement to a weightvalue of said trickle filter medium.